State prosecutors in Colorado said on Monday that they would not accept a plea bargain from alleged Aurora cinema gunman James Holmes, seeking death by lethal injection instead.

"For James Eagan Holmes in this case, justice is death," district attorney George Brauchler told a court in the Colorado city of Centennial, where Holmes' trial is scheduled to start in August.

Holmes' public defense team had said last week that they would offer a guilty plea in return for the promise that the 25-year-old was spared death by lethal injection. The lawyers said that they were prepared to fight the trial, pleading not guilty by reason of insanity, if the offer was refused.

"Mr. Holmes is currently willing to resolve the case to bring the proceedings to a speedy and definite conclusion for all involved," Holmes' defense lawyers wrote.

Prosecutors informally rejected this request within 24 hours, with the formal confirmation delivered in court on Monday. Brauchler was critical of the plea bargain, saying it was "filed for the intended purpose of generating the predictable pretrial publicity."

The heavily-publicized case was already subject to a public gag order.

"The only conclusion that an objective reader would reach … is that the defendant knows he is guilty, the defense attorneys know he is guilty and that both of them know that he was not criminally insane," Brauchler wrote.

August 5 restart

Holmes is accused of entering a movie theater during a premiere of the "Batman" movie "The Dark Knight Rises" on July 20, 2012 and opening fire on the crowded room. Twelve people died from gunshot wounds, another 58 were shot but survived, while 12 more suffered non-gunshot injuries as they sought to flee the cinema. Witnesses said Holmes used smoke grenades and then a variety of firearms.

Police investigating Holmes' apartment after the shooting found it booby-trapped with explosives. Prosecutors allege that the attack was meticulously planned.

Colorado is one of the US states to use the death penalty, with lethal injection the only permitted method. Three prisoners are currently on death row.

At a previous plea hearing in March, the judge entered a not-guilty plea on Holmes' behalf, after his legal team said they were not ready to issue a plea.

The shooting thrust US gun laws back into public and political focus, as did the Sandy Hook school shooting later in 2012.

msh/jlw (AFP, AP, Reuters)